Biochem EOC questions exam 1
Both prokaryotic and eukaryotic cells have all of the following except:
a. plasma membrane
b. genome of DNA
c. subcellular organells defined by membranes
d. ability to replicate
e. ability to transform external sources of energy into utilizale energy - ANSWER: c.
subcellular organells defined by membranes
Factors responsible for water molecule being a dipole include:
a. similarity in electron affinity of hydrogen and oxygen
b. tetrahedral structure of liquid water
c. magnitude of the H-O-H bond angle
d. ability of water to hydrogen bond to various chemical structures
e. difference in bond strength between hydrogen bonds and covalent bonds - ANSWER:
c. magnitude of the H-O-H bond
hydrogen bonds can be expected to form only between EN atoms such as oxygen or
nitrogen and hydrogen atom bonded to
a. carbon
b. an EN atom
c. hydrogen
d. iodine
e. sulfur - ANSWER: b. an EN atom
Which of the following is both a Bronsted acid and a Bronsted base in water?
a. H2PO4
b. H2CO3
c. NH3
d. NH4+
e. CL - ANSWER: A. H2PO4- can donae proton to be HPO42- or gain and become
H3PO4
Biological membranes are associated with all of the following except:
a. prevention of free diffusion of ionic solutes
b. release of proteins when damaged
c. specific systems for the transport of uncharged molecules
d. sites for biochemical reactions
e. free movement of proteins and nucleic acids across the membrane - ANSWER: e.
free movement of proteins and nucleic acids across the membrane
,Analysis of the composition of the major fluid compartment of the body shows that
a. the major blood plasma cation is K+
b. major cell fluid cation is Na+
c. one of the major intracellular anions is Cl-
d. one of the major intracellular anions is phosphate
e. plasma and cell fluid are all very similar in ionic composition - ANSWER: d. one of the
major intracellular anions is phosphate
Components of the electron transport system and oxidative phosphorylation are found
associated with the
a. outer mitochondrial membrane
b. inner mitochondrial membrane
c. mitosol
d. peroxisomes
e. protein synthetic components - ANSWER: b. inner mitochondrial membrane
which of the following is a characteristic of mitochondria?
a. inner membrane forms cristae and contains small spheres attached by stalks on the
inner surface
b. only the outer membrane has transmembrane system for translocation of metabolites
c. mitosol is relatively inert metabolically
d. mitochondrial DNA is similar to nuclear DNA in size and shape
e. mitochondria have no role in apoptosis - ANSWER: a. inner membrane forms cristae
and contains small spheres attached by stalks on the inner surface
Lysosomal enzymes
a. are hydrolases
b. usally operate at acidic pH
c. are normally isolated from their substrates by the lysosomal membrane
d. can lead to cellular digestion if the lysosomal membrane is disrupted
e. all of the abone - ANSWER: e. all of the above
Individual lysosomal enzymes are missing in a number of generic disease referred to as
lysosomal storage diseases. In these diseases
a. the defect is an inability to direct enzymes to the lysosome after synthesis
b. lysosomes of affected cells become enlarged with undigested materials
c. lipofuscin or "wear and tear pigment" accumulates in cells
d. any material taken into the lysosome will accumulate
e. residual bodies contain the products of digestion - ANSWER: b. lysosomes of
affected cells become enlarged with undigested materials
peroxisomes have a role in all of the following except
a. oxidation of very longchain fatty acids
b. synthesis of glycerolipids
c. hydrolysis of cholesteryl esters
d. oxidation of D-amino acids
, e. oxidation of uric acids - ANSWER: c. hydrolysis of cholesteryl esters (this is in
lysosomes
One of the roles of peroxisomes is to render H2O2 nontoxic by:
a. oxidizing amino acids with O2
b. action of enzyme catalase
c. transporting H2O2 from blood into peroxisomes
d. the action of cathepsins
e. shortening of fatty acid chain - ANSWER: b. action of enzyme catalase
If a weak acid is 91% neutralized at pH 5.7, what is the pKprime of the acid? -
ANSWER: If neutralized, 91 parts present as conjugate base and 9 remain as the
undissociated acid. Thus the conjugate base/acid ratio is 10:1. Substituting this ration
into Henderson-Hasselbalch gives 5.7=pK + log(10/1), so pK=4.7.
If normal plasma is pH of 7.4 and normal (CO2) is 1.2 mM, what is the normal (HCO3-).
The pK prime is 6.1. - ANSWER: CO2 is conjugate acid and HCO3- is conjugate base,
so 7.4=6.1+log(x/1.2) (Solve for x):: 24mM
1. All of the following are correct about a peptide bond except
a. it exhibits partial double bond character
b. it is more stable in the cis than in the trans configuration
c. it has restricted rotation around the carbonyl carbon to nitrogen bond
d. it is planar
e. in proline, the nitrogen is attached to the side chain. - ANSWER: B. it is more stable
in cis than in the trans configuration
2. In an a-helix,
a. side-chain groups can align to give a polar face
b. each peptide bond forms two H bonds
c. there are 3.6 amino acids/turn
d. all of the above
e. none of the above - ANSWER: D. all of the above
3. chaperone proteins
a. all require ATP to exert their effect
b. cleave incorrect disulfide bonds, allowing correct ones to subsequently form
c. guide the folding of polypeptide chains into patterns that would be thermodynamically
unstable without the presense of chaperones
d. of the Hsp70 class are involved in transport of proteins across mitchondrial and
endoplasmic reticulum membranes
e. act only on fully synthesized polypeptide chains - ANSWER: D. of the Hsp70 class
are involved in transport of proteins across mitochondrial and ER membranes
4. Proteins may be separated according to size by
a. isoelectric focusing
Both prokaryotic and eukaryotic cells have all of the following except:
a. plasma membrane
b. genome of DNA
c. subcellular organells defined by membranes
d. ability to replicate
e. ability to transform external sources of energy into utilizale energy - ANSWER: c.
subcellular organells defined by membranes
Factors responsible for water molecule being a dipole include:
a. similarity in electron affinity of hydrogen and oxygen
b. tetrahedral structure of liquid water
c. magnitude of the H-O-H bond angle
d. ability of water to hydrogen bond to various chemical structures
e. difference in bond strength between hydrogen bonds and covalent bonds - ANSWER:
c. magnitude of the H-O-H bond
hydrogen bonds can be expected to form only between EN atoms such as oxygen or
nitrogen and hydrogen atom bonded to
a. carbon
b. an EN atom
c. hydrogen
d. iodine
e. sulfur - ANSWER: b. an EN atom
Which of the following is both a Bronsted acid and a Bronsted base in water?
a. H2PO4
b. H2CO3
c. NH3
d. NH4+
e. CL - ANSWER: A. H2PO4- can donae proton to be HPO42- or gain and become
H3PO4
Biological membranes are associated with all of the following except:
a. prevention of free diffusion of ionic solutes
b. release of proteins when damaged
c. specific systems for the transport of uncharged molecules
d. sites for biochemical reactions
e. free movement of proteins and nucleic acids across the membrane - ANSWER: e.
free movement of proteins and nucleic acids across the membrane
,Analysis of the composition of the major fluid compartment of the body shows that
a. the major blood plasma cation is K+
b. major cell fluid cation is Na+
c. one of the major intracellular anions is Cl-
d. one of the major intracellular anions is phosphate
e. plasma and cell fluid are all very similar in ionic composition - ANSWER: d. one of the
major intracellular anions is phosphate
Components of the electron transport system and oxidative phosphorylation are found
associated with the
a. outer mitochondrial membrane
b. inner mitochondrial membrane
c. mitosol
d. peroxisomes
e. protein synthetic components - ANSWER: b. inner mitochondrial membrane
which of the following is a characteristic of mitochondria?
a. inner membrane forms cristae and contains small spheres attached by stalks on the
inner surface
b. only the outer membrane has transmembrane system for translocation of metabolites
c. mitosol is relatively inert metabolically
d. mitochondrial DNA is similar to nuclear DNA in size and shape
e. mitochondria have no role in apoptosis - ANSWER: a. inner membrane forms cristae
and contains small spheres attached by stalks on the inner surface
Lysosomal enzymes
a. are hydrolases
b. usally operate at acidic pH
c. are normally isolated from their substrates by the lysosomal membrane
d. can lead to cellular digestion if the lysosomal membrane is disrupted
e. all of the abone - ANSWER: e. all of the above
Individual lysosomal enzymes are missing in a number of generic disease referred to as
lysosomal storage diseases. In these diseases
a. the defect is an inability to direct enzymes to the lysosome after synthesis
b. lysosomes of affected cells become enlarged with undigested materials
c. lipofuscin or "wear and tear pigment" accumulates in cells
d. any material taken into the lysosome will accumulate
e. residual bodies contain the products of digestion - ANSWER: b. lysosomes of
affected cells become enlarged with undigested materials
peroxisomes have a role in all of the following except
a. oxidation of very longchain fatty acids
b. synthesis of glycerolipids
c. hydrolysis of cholesteryl esters
d. oxidation of D-amino acids
, e. oxidation of uric acids - ANSWER: c. hydrolysis of cholesteryl esters (this is in
lysosomes
One of the roles of peroxisomes is to render H2O2 nontoxic by:
a. oxidizing amino acids with O2
b. action of enzyme catalase
c. transporting H2O2 from blood into peroxisomes
d. the action of cathepsins
e. shortening of fatty acid chain - ANSWER: b. action of enzyme catalase
If a weak acid is 91% neutralized at pH 5.7, what is the pKprime of the acid? -
ANSWER: If neutralized, 91 parts present as conjugate base and 9 remain as the
undissociated acid. Thus the conjugate base/acid ratio is 10:1. Substituting this ration
into Henderson-Hasselbalch gives 5.7=pK + log(10/1), so pK=4.7.
If normal plasma is pH of 7.4 and normal (CO2) is 1.2 mM, what is the normal (HCO3-).
The pK prime is 6.1. - ANSWER: CO2 is conjugate acid and HCO3- is conjugate base,
so 7.4=6.1+log(x/1.2) (Solve for x):: 24mM
1. All of the following are correct about a peptide bond except
a. it exhibits partial double bond character
b. it is more stable in the cis than in the trans configuration
c. it has restricted rotation around the carbonyl carbon to nitrogen bond
d. it is planar
e. in proline, the nitrogen is attached to the side chain. - ANSWER: B. it is more stable
in cis than in the trans configuration
2. In an a-helix,
a. side-chain groups can align to give a polar face
b. each peptide bond forms two H bonds
c. there are 3.6 amino acids/turn
d. all of the above
e. none of the above - ANSWER: D. all of the above
3. chaperone proteins
a. all require ATP to exert their effect
b. cleave incorrect disulfide bonds, allowing correct ones to subsequently form
c. guide the folding of polypeptide chains into patterns that would be thermodynamically
unstable without the presense of chaperones
d. of the Hsp70 class are involved in transport of proteins across mitchondrial and
endoplasmic reticulum membranes
e. act only on fully synthesized polypeptide chains - ANSWER: D. of the Hsp70 class
are involved in transport of proteins across mitochondrial and ER membranes
4. Proteins may be separated according to size by
a. isoelectric focusing
